The aircraft of World War I were constructed from wood frame and had high quality linen stretched over it. To seal and protect this linen from the elements it was 'doped' with a cellulitic covering. The dopings used by the British in World War I were commonly known as PC10, PC12 and CDL. Where the PC is believed to have stood for protective coating, and CDL stands for clear doped linen. These were applied over the linen cloth of the wings, fuselage and tail of the aircraft.

The Australian Flying Corps [AFC] aircraft were all from British stock and factories. Consequently the dopings for the AFC aircraft were the same as the Royal Air Force [RAF], Royal Flying Corps [RFC] and Royal Naval Air Service [RNAS]. These dopings were commonly PC10 on the upper surfaces and CDL under the wings and elevators.

PC10 is a bit of a slippery colour for historians to nail down as it changed from a brown to green shade as the war progressed. Additionally as it was subject to weathering it browned in colour.

Another issue is that quality control was not the same in 1916 as it is in modern factories that have the benefits of digital technology and statistical process control. PC10 was very definitely a bucket chemistry proposition.

Bristol Fighter of No.1 Sqn AFC in the protective covering of PC10 doping. The engine cowl is painted in battleship grey.

For one hundred gallons of PC10 the recipe is:

260 pounds nitro Cellulose syrup

74 pounds of pigments in the following proportions:

40 pounds yellow ochre
30 pounds umber
2 pounds 8 ounces Red Ochre
1 pound 8 ounces Chinese Blue

Which was then added to:

20 gallons Acetone or Methyl ethyl ketone
15 gallons Amyl Acetate
15 Gallons benzol
15 gallons Methylated spirit

As can be seen from the 'recipe' it is more like baking a cake than the precision of modern factories which produce identical products 24/7 with minimal variation.

The AFC squadrons in France were very uniform in their dopings; largely being with PC10 upper and CDL lower with either polished or grey cowls. The training squadrons in England had higher variation including red, white and black-and-white checkered aircraft.

The anomaly is No.1 Squadron AFC in the Middle East. They seemed to go through phases where aircraft were relatively uniform in dopings but outside of the standards of the AFC/RFC squadrons in France.

For instance their BE2s and BE12s appear to be uniformly CDL all over until they went through a period where PC12 - PC10s reddish cousin - started appearing on their upper surfaces. The Martinsydes in No.1 squadron went through a similar phase. One aircraft it seems was CDL lower, PC12 upper and a PC10 tailfin - complete with white serial.

Martinsyde G100 of No.1 Sqn AFC with PC12 upper surfaces and PC10 tail. Profile is taken from a photo in One Airman's War

The Martinsydes then appear to have been standardised on all-over CDL before the Bristol Fighter's made their appearance in the squadron. Initially the Bristol Fighters had a mix of white and PC10 markings.

Bristol Fighter A7194 of No.1 Sqn AFC with white and PC10 upper surfaces.

Like the Martinsyde, the Bristol Fighters became standardised in the PC10 uppers and CDL lowers, though one aircraft was recorded as being yellow all over, there has been no photographic evidence of the 'yellow peril' Biff. It may have been ochre, CDL or erroneously reported as yellow.

The Martinsyde G100s and G102s started arriving in No.1 Squadron AFC in October 1916. Richard Williams recalls his first flight of one in the theatre. They had a mixture of dopings, appearing to be mixes of CDL, PC10 and PC12s until CDL became the standard in mid-1917.

The Martinsyde was intended to be a long-range reconnaissance aircraft and had a large fuel tank fitted. This gave it the capability of flying for five and a half hours. The extra weight of the fuel meant the aircraft required greater wing surface area.

This affected its ability to act as a scout, but when the G100 was designed, the normal aircraft on the western front were BE2s and German C Type aircraft. The advent of the forward firing tractor scout made the original specification for the Martinsyde obsolete.

The Martinsyde was originally used in the fighter-escort role by No.27 Sqn RFC, but was out-performed by the Fokker Monoplanes. The squadrons in France equipped with the type began to use it predominantly in the bombing role.

Martinsyde's began to be sent to the Middle East in 1916, passing on to the two squadrons in Macedonia, the four in Palestine and three in Mesopotamia.

No.1 Sqn's Martinsydes started arriving from X Aircraft Park in Egypt in October of 1916. Richard Williams recalls it arriving in his flight;

Soon after one [Martinsyde] was allotted to No.1 Squadron, and it was delivered to us by a pilot F.F. Minchin ... This aircraft was allotted to my flight and being a single-seater I could only question Minchin as to its characteristics.

It was, and still is, often the case that a pilot who has flown a new type of aircraft when talking to another interested in flying it takes the attitude .. that he flies it without difficulty but he is not quite sure about anyone else being able to do so.

In reply to my questions Minchin assured me that the aircraft must be placed on the ground at 60 miles an hour.

This, of course, was a much higher speed than we were accustomed to - about 50 percent faster - but one had to take his word.

I tried it and found myself using up landing space at an alarming rate. I took off and went round again. This time I made sure of putting the wheels on to the very edge of the landing area but again the ground was running out too fast and I went around a third time.I had the same experience but I took longer to decide to go around again.

There was a telegraph line of about a dozen wires running across the end of the aerodrome and having taken off I flattened out to get a little extra speed to zoom over the wires, when CRASH! and I was hanging on the belt of the aircraft which was upside down on the ground.

I had hit a bell tent of a small Egyptian labour corps camp in the corner of the aerodrome which I had not seen. This aircraft was particularly blind ahead.

Luckily the tent wrapping around the undercarriage softened the fall, the petrol tank did not burst and there was no fire.

I found out subsequently, when the next one arrived, that there was no need - in fact it was foolish - to land this aircraft at anything like 60 miles an hour.

Anyway none of the landing grounds used in those days was large enough to take that speed. We had no brakes, of course.

The British pilots on the Western Front called the Martinsyde the Elephant. The Australians of No.1 came to call it the 'tinsyde.

It seems that the 'tinsydes came in a mix of Clear Doped Linen (CDL), PC12 and PC10. For instance G100 7488 has been photographed in all over CDL, but also (on its back) with a warm coloured fuselage which is possibly PC12.

A curious example is 7477 which was photographed with (also on its back) which a dark tail fin, a warm fuselage and top wing covering and CDL undersides.

It appears that in the later period of the Martinsydes serving with standardised on CDL for the upper, lower and fuselage surfaces.